Recent advances have been made to allow direct streaming of video and audio directly from one wireless communication enabled device to another. One such system is known as “Miracast.” Miracast is a trademark for a wireless (e.g., IEEE 802.11 family of wireless protocols or “Wi-Fi”) display protocol promulgated by the Wi-Fi Alliance. As used herein, the term Miracast refers to the current form of the Wi-Fi Alliance's display sharing protocol, also known as Wi-Fi Display (WFD). The Miracast specification is designed for streaming any type of video bitstream from a source device (or “source”) to a sink device (or “sink”). As one example, a source may be a smart phone, and a sink may be a television set. Although client devices generally communicate through an access point (AP) device in IEEE 802.11 wireless networks, certain protocols (such as Wi-Fi Direct) may support direct device communications. The Miracast system uses such protocols for sending display data from one device to another, such as from a smart phone to a television or computer, or vice-versa. The Miracast system involves sharing the contents of a frame buffer and speaker audio of the source to a remote display/speaker device (sink) over a Wi-Fi connection.
The Miracast protocol involves the source capturing the RGB data from the frame buffer and any PCM (Pulse Coded Modulation) audio data from the audio subsystem. The content of the frame buffer may be derived from application programs or a media player running on the source. The source may then compress the video and audio content and transmit the data to the sink. On receiving the bitstream, the sink may decode and render the content on its local display and speakers.
When a user plays an audio/video clip locally on a source (e.g., a Miracast capable source), the bitstream may be decoded and rendered locally on the display of the source, and then the audio/video content may be captured, re-encoded, and streamed to a sink (e.g., a Miracast capable sink) at the same time. The sink may then decode and render the same content on its display and speakers. Such operation is often called the “mirroring” mode.